Microwave phase conjugation using nonlinearly loaded wire arrays

Microwave phase conjugation can be achieved using pumped nonlinear surfaces composed from wires or printed elements loaded with semi-passive nonlinear loads like diodes or diode pairs (Ding, W. et al., IEEE MTT-S Microwave Symp. Dig., vol.3, p.1851-4, 2001). To the authors´ knowledge, such structures have not been given theoretical consideration before. We outline an analysis technique based on combining Floquet and Volterra series methods which can be used to determine the scattering characteristics of a double periodic array of wires loaded with generalized transfer characteristic weakly nonlinear elements. Namely, we consider a planar infinite double periodic array of straight thin wires loaded with lumped nonlinear components characterized by a series law functional dependence between the current through the component and the voltage impressed on its terminals by the plane incident wave. Phase conjugation occurs due to the mixing process between the weak incident signal wave and a stronger pumping wave. This approach can be easily generalized to periodic arrays with any type of nonlinearly loaded scattering elements, including patches or bent wires, thus opening up the possibility to control additionally the frequency band and polarization properties of scattered phase conjugated waves.